人工湿地植物生物质资源能源化利用潜力评估

通过测定不同人工湿地植物的纤维素组分和热值,并采用NaOH–酶解工艺研究不同人工湿地植物水解液组分,对在人工湿地技术体系中起重要作用的湿地植物能源化利用潜力进行系统评估.结果显示,15种人工湿地植物的纤维素含量在19.78%～36.9%之间,半纤维素含量在4.51%～19.67%之间,木质素含量在10.79%～20.47%之间,具有与玉米秸秆相当的热值,其热值在14.002～17.839 MJ/kg之间.在NaOH–酶解工艺条件下,不同人工湿地植物水解液中存在5种糖类组分,主要为葡萄糖和木糖.研究表明,人工湿地植物是一种较好的生物质资源,可通过生物质固体成型燃料技术、沼气技术和燃料乙醇技术加以利用,进而建立人工湿地植物生物质资源能源化藕联利用模式.图2表2参22     

Development of a coupled reservoir operation and water diversion model: Balancing human and environmental flow requirements

Maintaining a natural flow regime helps preserve the health of riverine ecosystems. Conventional studies on reservoir operations have focused mainly on identifying optimal operational schemes for satisfying human water demands. To systematically reflect the ecological effects of both natural and human-induced hydrologic alterations, water diversions downstream of the reservoirs should be considered as well. This research focused on a coupled reservoir operation and water diversion (CROWD) model, created through the integration of a reservoir operation model and a water diversion model. The proposed model considers both human and environmental flow requirements, and represents a compromise that balances ecological protection (preservation of the natural flow regime of a river) and human needs (reduced water shortages). In the reservoir operation model, the reservoir space is divided into three zones and different operating rules are developed for directing reservoir operation when water levels are in different zones; in the water diversion model, different water users are assigned different supply priorities with the instream flows no more than the minimum environmental flows having the highest priority; and the two models are coupled by the water mass balance between the two hydraulic facilities. The non-dominated-sorting genetic algorithm II (NSGA-II) was used to determine the parameters of the developed CROWD model and the model was applied to support the joint operational management of the Tanghe Reservoir and the Liaoyang Diversion in the Tang river basin, China. The resulting reservoir operation and water diversion schemes indicate that the CROWD model is useful for optimizing the operation of reservoirs and water diversion schemes. Moreover, it helps to analyze tradeoffs between human and environmental water needs, resulting in solutions that reduce the risk of water shortages and minimize ecological integrity disturbances.     

Effects of alfalfa coverage on runoff, erosion and hydraulic characteristics of overland flow on loess slope plots

An evaluation of the interactions between vegetation, overland and soil erosion can provide valuable insight for the conservation of soil and water. An experiment was conducted to study water infiltration, runoff generation process, rate of sediment erosion, and hydrodynamic characteristics of overland flow from a sloping hillside with different draw-off discharges from alfalfa and control plots with 20° slope. The effect of alfalfa on runoff and sediment transport reduction was quantitatively analyzed. Alfalfa was discussed for its ability to reduce the overland flow scouring force or change the runoff movement. Compared to the bare-soil plots, alfalfa plots generated a 1.77 times increase in infiltration rate. Furthermore, the down-slope water infiltration rate for the bare soil plots was higher than in the up-slope, while the opposite was found in the alfalfa plots. In addition, alfalfa had a significant effect on runoff and sediment yield. In comparison to the control, the runoff coefficient and sediment transportation rate decreased by 28.3% and 78.4% in the grass slope, respectively. The runoff generated from the alfalfa and bare-soil plots had similar trends with an initial increase and subsequent leveling to a steady-state rate. The transport of sediment reduced with time as a consequence of the depletion of loose surface materials. The maximum sediment concentration was recorded within the first few minutes of each event. The alfalfa plots had subcritical flow while the bare-soil plots had supercritical flow, which indicate that the capability of the alfalfa slope for resisting soil erosion and sediment movement was greater than for bare soil plots. Moreover, the flow resistance coefficient and roughness coefficient for the alfalfa plots were both higher than for the bare-soil plots, which indicate that overland flow in alfalfa plots had retarded and was blocked, and the flow energy along the runoff path had gradually dissipated. Finally, the ability to erode and transport sediment had decreased.     

Environmental dispersivity in free-water-surface-effect dominated wetland: multi-scale analysis

Distinct from the case with width-dominated shallow wetland flows, the longitudinal evolution of contaminant concentration in the most-typical pattern of wetland as dominated by free-water-surface-effect is characterized by a multi-scale analysis in the present study. An environmental dispersion model for the evolution of the mean concentration is deduced as an extension of Taylor's classical formulation by Mei’s multi-scale analysis. Corresponding environmental dispersivity is found identical to that determined by the method of concentration moments.     

Restoration of hyper-eutrophic water with a modularized and air adjustable constructed submerged plant bed

A modularized and air adjustable constructed submerged plant bed (CSPB) which can be used to restore the eutrophic water is introduced in this paper. This plant bed helps hydrophyte grow under poor conditions such as frequently changed water depth, impaired water transparency, algae bloom and substantial duckweed in summer, which are not naturally suitable for growing hydrophyte. This pilot study in Waihuan River of Tianjin, China, revealed that reduction of Chemical Oxygen Demand (COD), Total Nitrogen (TN) and Total Phosphorus (TP) by the use of CSPB could be reached 30%–35%, 35%–40%, 30%–40% respectively in the growing season (from March to October) and 5%–10%, 5%–15%, 7%–20% respectively in the winter (from November to February) when the detention time was 6 d. The relationships between the concentration of COD, TN, TP and the detention time fit the first-order kinetic equation well and the coefficients of determination (R²) were all above 0.9. The attenuation coefficients k of the kinetic equation were a function of the water temperature. When the water temperature was quite low or quite high, k was not significantly changed with increasing or decreasing water temperature. While when the temperature was in a moderate range, an increase or decrease of water temperature would lead to a rapid increase or decrease in k.     

水深梯度对荆三棱(Scirpus yagara)生长的影响

研究湿地植物对水深梯度的响应对于湿地修复具有重要的指导意义.在南四湖湖边滩地上的人工修复湿地中开展水深梯度对荆三棱(Scirpus yagara)生长的影响研究,试验观测水深分别为-10、0、10、20、30 cm共5个梯度.结果显示:随着水位的升高,1)荆三棱的株高、基茎、叶长和叶宽均有所增加,当水位大于10 cm时各项指标增加更为显著;2)生物量呈增加趋势,而根茎比则逐渐减小,水位为30 cm时的生物量和根茎比分别为-10 cm时的2.67倍和58.15%;3)叶绿素含量总体呈增加趋势,但在不同水位间的差异不明显(P>0.05);4)叶绿素荧光方面,最大光化学量子产量Fv/Fm均在0.75以上,光化学淬灭qP和非光化学淬灭qN分别呈现出升高和下降的趋势.结果表明,在试验所设置的水位条件下(-10～30 cm),荆三棱的生长没有受到水深梯度增加的显著影响,相反表现出随着水深的增加而生长更好的趋势.可见,在试验设置的水深梯度范围内,相对较高的水位有利于荆三棱的生长,因此在湿地管理中应控制适当的高水位以利于其种群的生长和稳定.     

Removal of trace elements in three horizontal sub-surface flow constructed wetlands in the Czech Republic

Between March 2006 and June 2008 removal of 34 trace elements was measured on a monthly basis at three horizontal-flow constructed wetlands in the Czech Republic designed to treat municipal wastewater. In general, the results indicated a very wide range of removal efficiencies among studied elements. The highest degree of removal (average of 90%) was found for aluminum. High average removal was also recorded for zinc (78%). Elements removed in the range of 50-75% were uranium, antimony, copper, lead, molybdenum, chromium, barium, iron and gallium. Removal of cadmium, tin, mercury, silver, selenium and nickel varied between 25 and 50%. Low retention (0-25%) was observed for vanadium, lithium, boron, cobalt and strontium. There were two elements (manganese and arsenic) for which average outflow concentrations were higher compared to inflow concentrations. Reduced manganese compounds are very soluble and therefore they are washed out under anaerobic conditions.     

环境因素对芦苇湿地CH4排放的影响

用封闭式箱法对辽河三角洲芦苇湿地温室气体CH4 排放进行了长期观测 .结果表明 ,CH4 排放有明显的季节变化规律 ,平均通量为 52 0 μg·m- 2 ·h- 1.土壤产CH4 活性主要发生在 0～ 5cm土层中 ,并随土层深度的增加而显著下降 .CH4 排放受环境因素影响很大 ,土壤氧化还原电位在 -1 1 0mV时就有CH4 排放 ,其排放量随氧化还原电位的下降而增加 .另外 ,随着淹水深度的增加 ,CH4 排放反而减少 .在测定期内 ,CH4 排放与温度呈明显的正相关 (R2 =0 1 96,n =2 1 ,P <0 .0 5) .     

中外大河河口湿地保护与利用初探

在分析研究河口湿地形成与演变、河口湿地生态系统特征的基础上 ,对中外大河河口湿地保护与利用现状进行了初步研究 ,以期为中国河口湿地保护与利用提供一定的借鉴和启示     

Kinetic-spectrophotometric determination of free cyanide by stopped-flow reversed flow injection analysis

A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.